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Flashcards in Speciation Deck (11)
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1
Q

Fossils can be formed from:

A
  • hard body parts such as shells or bones
  • parts of organisms which haven’t decayed (dead plants and animals can be preserved in tree resin or ice.
  • casts or impressions (foot prints or burrows)
2
Q

What is a fossil?

A

Preserved remains of a dead plant or animal.

3
Q

What can scientists learn from fossils?

A

How organisms have changed as life developed on earth.

4
Q

What can cause a species to become extinct?

A
  • new diseases
  • new predators
  • new, more successful competitors
  • changes to environment/climate
  • catastrophic events (eruptions or asteroids)
  • human activities
5
Q

How did the dodo become extinct?

A

Island colonised by humans. Humans ate them as they were easy to catch. New competitors (rats, cats) ate their eggs.

6
Q

New species can arise due to …..

A

Isolation

7
Q

What is genetic variation?

A

Where each population has a wide range of alleles that control their characteristics.

8
Q

What is natural selection?

A

Where the alleles which help an organism to survive are selected in each population.

9
Q

What is speciation?

A

Where the populations become so different that successful interbreeding cannot happen anymore.

10
Q

Which conditions are needed for fossilisation?

A

Low oxygen levels and cold.

11
Q

What’s the most likely reason that early life forms left few traces behind?

A

Most animals were soft bodied so didn’t fossilise well.